problem with fuel system wiring

DGB47 · Post by **DGB47** » 05 Jun 2013, 10:26

I've been searching the site for awhile looking for answers to my problem, but haven't found a match yet.
I have a 89 760 turbo with 202K miles.
a few weeks ago the main fuel pump started getting load and sure enough it seemed to quit a few days later, but before it did the fuel relay started buzzing really loudly. My first thought was to replace the relay since it was the least expensive, but that didn't change anything, so, I changed out the main fuel pump and filter, still didn't work.
I then pulled the tank pump and sending unit, which was in bad shape, pretty rusted through, no ground to the pump so, pump had not been working for who knows how long and replaced.
Still pumps were not coming on when putting the key in the on position. I jumped the 87/2 and 30 terminals at the relay w/o the key in the ignition and the main pump works. I then figured my new relay was the problem, so, I got another one, nothing. No voltage to the pumps when the relay is installed and the key is in the on or start position.
Been looking for the fuel wiring diagram for my specific model and possibly a step by step procedure of what to check next. The engine is the B230FT and it has the LH-Jetronic fuel injection system.
Can someone tell me where to look/test next, is it the ECU or is there something else between that could be the problem.
I have taken quite a bit of the dash and under dash apart and pulled the fuse panel out and relay panel as well checking as much of the wiring as possible for bad or loose connections.
Thanks for reading, I certainly appreciate all of you who take the time to help others with your knowledge.

lummert · Post by **lummert** » 05 Jun 2013, 23:00

maybe something like this: Try Figure 3.
http://www.v8volvo.se/mekartips/volvo/F ... tchell.pdf

Jpawww · Post by **Jpawww** » 06 Jun 2013, 22:32

Here is the British site that has wonderful diagnostics for checking the ECU. There even exists on there an interchange database and hacks to bypass common problems.
http://www.volvoclub.org.uk/faq/EngineFIComputer.html
Hope that helps!
Also have you run the OBD codes from the inboard diagnostics? They are rarely helpful, but occasionally can start you in the right direction.
Also I believe on my 240 that if my neutral safety switch isn't set just right I will get no crank but can't recall if I hear the pumps. Ill look in to that and get back. But out of curiosity will it crank?

DGB47 · Post by **DGB47** » 06 Jun 2013, 23:43

Haven't any diagnostics and yes it does crank. Thanks for the info.

DGB47 · Post by **DGB47** » 20 Jun 2013, 07:06

Turned out the wiring for the fuel system is fine. Apparently power only goes to the pumps when your cranking the engine over rather then just putting it in the start position. Also reason for not starting was the the sending unit I purchased from a salvage yard was completely plugged in the outlet line. Mechanic said this is due to the ethanol in the gas.
Thanks for your help.